Camouflage



naturally of a different shade. Y use of infra-red photography in military reconinfra-red region.

Patented Oct. 31, 1944 umreo STATES PATENT. OFFICE,

CAMOUFLAGE Walter C. Granville, New Stork, N. Y., assignorto Interchemical CorporatlomNcw York, N. Y., a V v corporation of Ohio No Drawing. Application July s, 1942, Serial 3.450.139

14 01mm. (L loll-+287) naisance makes 'itnecessary to employ'paints for camouflage which have substantially the same spectral reflectance throughout the entire visible spectrum and well into the infra-red region as has the foliage for which the paint is intended to be mistaken. Although some pigmented compositions will reflect infra-red energy to a greater extent than visible light they are not neces-- sarily suitable for camouflage because thespectral reflectance characteristics of vegetation are not only high in the infra-red'region of the spectrum but they show a-peculiar, sharp absorption at the long' wave end oi. the visible spectrum (i. e. 680 to 730 mu. wave length).

This invention provides a coating composition I which may be used to match any color or foliage from the lightest green through darker shades to olive and even brown, and will exhibit substantially the same spectral reflectance characteristics as the foliage it matches,throughout the visible spectrum and extending well into the The pigment composition of this invention de- 730 mu, a high degree of transmittance in the wave length region from about 740 to about: 900 mm, the maximum absorption falling within the rangeof about 670 to'about 690 mu. and showing increasing transmittance from the point of maximum absorption to about450 mu. However, most of these colorants are lacking in light fastv ness so that their use incamoufiage coatings is extremely limited and is often entirely impracticable. We have discovered that there is asmall groupof colorants within the larger group described which not only have spectral absorption characteristics very similar to that of natural U foliage in the region from 600 to 730 mu., but

, latter are the most light-stable, In many cases they also are sufllciently light-fast to make them useful in theordinary camouflage coatings.

The colorants of the light-fast groupare obtained by coupling tetrazotized dianisidine with beta oxy naphthoic acid, the anilide of beta oxy naphthoic acidor with alkoxy substituted anilides of'beta oxy naphthoic acid, of which the metallizing the colorant produces evenfurther light jfastness and for this purpose copper and 'nickel'are preferred. Of this group of colorants "five have been found which are particularly good.

They are the compounds resulting from the couthe anilide, the o-anisidide, the

pends for its infra-red reflectance characteristics on the inclusion of certain deep blue colorants,

the particular visible shade of the composition being adjusted by the addition ofvarious other colorants generally of red to yellow color. In practice, it is usually desirable to add various amounts of white or inert pigments to increase the reflectivity and opacity ofthe composition and to take advantage of the strong coloring power of these colorants. I V a 1 The colorants. on whose characteristics this invention is based are the deep blues obtained by coupling. tetrazotized dianisidine with beta oxy naphtho'ic acid and certain arylamidesof beta oxy naphthoic acid. The colorants which come within this group are the only ones so far known which exhibit the sharp spectralabsorption characteristics in the region considered together with the necessary characteristics in the visible region. The spectral absorption characteristics of these blues may be described as having a major transition from maximum light absorption to maximum transmittance occurring in the wave length region from about 680 to about weight.

pling of dianisidine with beta oxy naphthoic acid, o-phenetidide and the 2,5 dimethoxy anilide of beta oxy naphthoic acid.

Any of the commonly known yellow and red colorants'which are suflicientlylight-fast, may be mixed with theblues described above to. produce various shades of greens and browns. For this purpose, yellows and reds of thecadmium and iron oxide series and someyellows of the Hansa series, especially the compounds resulting from the coupling of ,azotized arylmonoamines with acetoacetic arylamides, are suitable;

Although the preparation of particular camouflage compositions is apparent from the above description, atypical formulation which produces a color approximating Greens Nos. 1 and 2 of the U. S. Army Engineer Board Specification T-1213 is as follows:

The proportions are based on the dry pigment Per cent tucky Color & Pigment Co.) 50 Titanium dioxide (chalk resistant) 35 The above pigment mixture can be dispersed in any conventional vehicle, such as oleoresinous varnishes, long ol alkyd varnishes, nitrocellulose lacquers and the like.

The blue pigment used in this formulation was tetrazotized d'ianisidine'coupled with the 2;5 dimethoxy anilide of beta oxy naphthoic acid.

Other variations and modificationswill be apparent to those skilled in the art, and the invention should not be limited other than fined in'the appended claims. I claim:

which comprises a binder and mixture of colorants, said colorants selected so thatthe mixture appears to the eye and to infra-red photography-- to have the color of vegetable matter, the essen tial colorant which reproduces the spectral reflectivity of chlorophyll-bearing foliage in the wavelength region from 550 "to -800"mu. comprising a material whose major transition from maximum light absorptionto maximum transmittance occurs in the wave length regionfrom -about 680 to 730 mu, said material being sub- 1 ,stantiaiiy transparent in'the wavelength region fromabout 'lw to' about 900 mughaving'the :m'aximum absorptionfalling within the range of -about 670 :to '690 mu." and beingof increasing transmittance from thefpoint of maximum absorption down to about "450 mu.,-said material I comprisinga-blue colorant of thegroup consisting of the compound formedby-coupling'tet razotized dianisidine with a member selected. from' the group consisting of beta oxy naphthoicacid, the anilide of beta oxy naphthoic acid and alkoxy -substitut'd anilides of 'beta oxyhaphthoic' acid,

and the metallized derivatives thereof with a group consisting of copper and 2. Composition-as claimed in claim- 1 wherein :1 said compound i's metalli zed with a metaljselected from the group consisting of copper and nickel. I Y 31 Composition showing substantially the refiect'ance' characteristics of; leafy, vegetation, which comprises a binde 1j and mixture'of colorantsi saidcolo'rants selected so that the ,miiiture appears to the eye andtofinfra redphotography to have the color of vegetable matter,.the essential colorantwhich reproduces the spectral reflectiv'ity of chlorophyll-bearing foliage Lin the wave length region from ,550fto 30o imu comprising the compound formed} by oouplingtet as de 1. Coating composition showing substantially I the reflectance characteristics of leafy vegetation, 3

from the group consisting of copper and nickel.

8. Composition of claim 6 wherein said compound is metallized with copper. M 9. Composition showing substantially the reflectance characteristics of leafy vegetation,

I which comprises a binder and mixture of color-,

ants, said colorants selected so that the mixture appears to the eye and to infra-red photography to have the color of vegetable matter, the essential colorant which reproduces the spectral reflectivity of chlorophyll-bearing foliage in the wave length regionfrom 550 7to 800 mu. comprising the compound formed by coupling tetra'zoti zed dianisidine with theganilide of beta oxy naphthoic acid.

g 10. Composition as claimed in claim 9 wherein said'compoundi's metallized with a metal selected from the group consisting of copper and nickel. 11 Composition of claim 9 wherein said compoundismetallized with copper; I 12. Composition showing substantially the reflectance characteristics of leafy vegetation, which'cornpr'is'es a binder and mixture of color- *ant s,' said colorants selected so that the mixture appears to'the eye and to infra-red photography to have the color of, vegetable mattenthe essential colorant which'reproduces the spectral re- -flectivity of chlorophyll bearing foliage in the wave length region from 550 to 800 mu; comprising a blue colorantof the groupconsisting of the compound formed by coupling tetrazotized dianisidine ,with the 2,5 dimethoxy anilide of "beta ox'y naphthoic acid, and the metallized derivativesthereof with a metal of, the group consiStin'g'pf copper and nickel.

. 13.,C0mposition showingsubstantially there- I fiectance, characteristics of leafy. vegetation,

, appears to the eye and to infra-red photography which comprises a binder and mixture of colorants, said colorants selected so that the mixture 1 to havethe color of vegetable matter, the essenrazotizedl dian'isidine with: his 2,5 "dimethoxy anilideof beta'oxy naphthoic acid.

Compositiinas claimed. in claim 3 wherein said compound is metallized with a metal selected from"theygroup consisting of copper andnickel.

, 5. Composition of claim 3 wherein said com- I 1 pound is metallized with copper.

,, a 6. Composition showing substantially the., re-

fiec'tancc characteristics of. leafy: =vegetati0n,

which comprises a binder andmixture oiv colorants, said colorant selectedsothrit the -1nix ture appears to the eye andto infra-red photography to have the color of vegetable matter, the

' essential colorant which reproduces the spectral tial colorant which reproduces the spectral reflectivity of chlorophyll-bearing foliage in the wave length region from 550 to-800 mu. com-'- .-prising a blue colorant of the group consisting of the compound formed by coupling tetrazotized dianisidinewith the 'ortho anisidide of beta oxy 'naphthoic acid, and themetallized derivatives thereof with ametal of the group consisting of c0DDr.;and nickel. t

. 114. Composition showing substantially the refiectance "characteristics of leafy vegetation,

- which comprises a binder and mixture of colorreflectivity of chlorophyll-bearing foliage in the wavelength region from 550 to 800 mu. comprismg the compound-formed by coupling tetrazotized dianisidine with l the ortho anisidideof beta oxy naphthoic acid. v 1' '7. Composition as claimed inl claim 6 wherein said compound is metallized with a metal selected -antssaid colorants selected so that the mixture appears to the eye, and to infra-red photography ;to have the color of vegetable matter, the essential colorant which reproduces the spectral refiectivity of "chlorophyll-bearing foliage in the wave length region from 550m 800 mu. comprising a blue colorantofthe group consisting of the compound formed by coupling tetra'zotized dianisidine with the anilide of beta 'oxy naphthoic acid, and themetallized derivatives thereof with 'am'etal of the group consisting of copper and nickel. I f

a WALTER c. GRANVILLE, 

